Researchers discover how biology modifies minerals

Researchers discover how biology modifies minerals

The biochemical process by which cyanobacteria acquire nutrients from rocks in Chile’s Atacama Desert has inspired engineers at the University of California, Irvine to think of new ways the microbes could help humans build colonies on the moon and on Mars.

Researchers from UCI’s Department of Materials Science and Engineering and Johns Hopkins University’s Department of Biology used high-resolution electron microscopy and advanced spectroscopic imaging techniques to gain a precise understanding of the how microorganisms modify both natural minerals and synthetic nanoceramics. A key factor, scientists say, is that cyanobacteria produce biofilms that dissolve magnetic iron oxide particles in gypsum rocks, then converting the magnetite into oxidized hematite.

The team’s findings, which are the subject of a recently published article in the journal Materials Today Organic, could pave the way for new biomimetic mining methods. The authors also said they see the results as a step towards using microorganisms in large-scale 3D printing or additive manufacturing at a scale useful in civil engineering in harsh environments, such as those in the Moon and Mars.

“Through a biological process that has evolved over millions of years, these tiny miners dig into rock, extracting minerals essential for physiological functions, such as photosynthesis, that enable their survival,” said corresponding author David Kisailus. , professor of materials at the UCI. science and engineering. “Could humans use a similar biochemical approach to obtain and manipulate the minerals we find valuable? This project led us in this direction. »

The Atacama Desert is one of the driest and most inhospitable places on earth, but Chroococcidiopsisa cyanobacterium found in gypsum samples collected there by the Johns Hopkins team, developed “the most amazing adaptations to survive its rocky habitat,” said co-author Jocelyne DiRuggiero, associate professor of biology at the University of Baltimore.

“Some of these characteristics include the production of chlorophyll which absorbs far-red photons and the ability to extract water and iron from surrounding minerals,” she added.

Using advanced electron microscopes and spectroscopic instruments, researchers found evidence of the presence of microbes in gypsum by observing how the minerals contained within were transformed.

“Cyanobacteria cells promoted magnetite dissolution and iron solubilization by producing abundant extracellular polymeric substances, leading to the dissolution and oxidation of magnetite to hematite,” DiRuggiero said. “Production of siderophores [iron-binding compounds generated by bacteria and fungi] was enhanced in the presence of magnetite nanoparticles, suggesting their use by cyanobacteria to acquire iron from magnetite. »

Kisailus said the way microorganisms process metals in their desolate home made him think about our own mining and manufacturing practices.

“When we extract minerals, we often end up with ores that can present challenges for the extraction of precious metals,” he said. “We frequently have to subject these minerals to extreme processing to turn them into something of value. This practice can be financially and environmentally costly. »

Kisailus said he is now considering a biochemical approach using natural or synthetic analogues of siderophores, enzymes and other secretions to manipulate minerals where only a large mechanical crusher currently operates. And jumping from there, he said there might also be a way to get microorganisms to use similar biochemical abilities to produce engineered material on demand in less-than-convenient places. .

“I call it ‘moon formation’ instead of terraforming,” Kisailus said. “If you want to build something on the moon, instead of having people do it, we could have 3D print media of robotic systems and then have microbes reconfigure it into something of value. This could be done without endangering human lives. »

He added that humans don’t always need to use Edisonian approaches to figure out how to do things.

“This is the main theme of my biomimetics and nanostructured materials laboratory. Why try to reinvent the wheel when nature has perfected it over hundreds of millions of years? said Kisailus. “We just have to extract the secrets and blueprints from what nature does and apply or adapt them to what we need. »

This project was funded by the Army Research Office and was aided by instruments made available by the Department of Energy’s Office of Science. The research team also included Wei Huang, a postdoctoral researcher from Kisailus’ lab group; Taifeng Wang, Ph.D., who recently graduated from UCI and is now employed at Intel; and Cesar Perez-Fernandez from the Department of Biology at Johns Hopkins University.